Algae Mostly SINGLE CELLED PHOTOSYNTHETIC AUTOTROPHIC Eukaryotes Algae

Algae Mostly SINGLE CELLED PHOTOSYNTHETIC AUTOTROPHIC Eukaryotes - Algae

Kingdom Protista Division Phycophyta (Algae) Phycology is the science that deals with the morphology, taxonomy, biology, and ecology of algae in all ecosystem. Characteristics of protists (algae) plant-like Ø Algae are called plant-like because they make photosynthesis, they contain chlorophyll and they produce their own carbohydrates given off oxygen. Ø Algae differs from protozoa which are also classified in the kingdom protista in manufacturing their food through the process of photosynthesis. Ø Algae are autotrophic protists. Ø Most algae are Aquatic (fresh water or sea).

Ø Although many species of algae are unicellular, some are large multicellular organisms. Ø Algae range in size from single-celled to large seaweeds (> 100 m). Ø Many of them show alternation of generations. Ø Most of them have flagella at some stages. Ø Algae vary from plants because they: - Lack well-organized tissues - Lack true roots, leaves or stems - Lack cuticle on epidermis Ø Algae are classified based on predominating pigments.

Rhodophyceae Xanthophyceae Algae classes Phaeophyceae Chlorophyceae

Class Rhodophyceae Color Nutrition Pigments Stored food Morphology Mostly pink to dark red Photosynthetic & few are parasitic Chlorophyll a carotenoid and phycoerythrin Floridean starch Many are branched multicellular thalli, Few are unicellular or colonial. Structure Cell wall with cellulose or pectic compound. Many contain calcium carbonate. No flagellate cell at all the life cycles Reproduction Sexual reproduction is oogamous (with no motile male and female gametes). Some reproduce asexually. Genera Polysiphonia Ecology Mainly marine, few fresh water Live at greater depth than other photosynthetic organisms. Few number are parasite. Importance Source of useful chemicals Rich in proteins, vitamins, and minerals for food and medicinal purposes. Agar (polysaccharide used in capsules, culture and gels) Agarose: gels used in gel electrophoresis. Carageenan: used in paints, ice cream and as smoothing agent.

Polysiphonia n= female plant Makes n carpospres that become 2 n zygotes 2 n –plant n= male plant Makes n spermatia N tetraspores

Genus: Polysiphonia

2 n – plant makes (n) tetraspores

female plant (n) makes carpospores that become 2 n zygotes male plant (n) makes spermatia

Cystocarp

Polysiphonia tetraspora

Class Phaeophyceae (brown algae) Color Brown largest algae “seaweeds” Nutrition Photosynthetic Pigments Chlorophyll a and c carotenes and fucoxanthin Stored food Laminarin (oily carbohydrates), mannitol, glycerol and sometimes fats. Morphology Most are large multicellular compose of root-like, stem-like and leaf like organs (holdfast, stipe and blade respectively). Few are microscopic Structure Cell wall with cellulose layer surrounded by alginate. Many have some tissue specialization (some species contain sieve tube and meristematic) Reproduction Asexual and sexual (isogamous, anisogamous and oogamous) Most forms have alternation of generation: Diploid sporophytes which produce spores within sporngia & Haploid gametophytes which form motile (with 2 flagella) male and female gametes within gametangia. Genera Ectocarpus, Fucus & Sargassum Ecology Almost are marine species. Importance Fertilizer Source of commercial Iodine food in Japan Agar (polysaccharide used in capsules culture and gels) Source of poly sacchride algin (used as thickner in many products as ice cream, paint, toothpaste, shampoo, processing of natural and synthetic rubber )

Fucus Gas Bladder

Male Plant with Antheridia • Fucus conceptacle

Female Plant with Oogonia conceptacle

Class Xanthophyceae Color Nutrition Pigments Stored food Morphology Yeallow-green Photosynthetic Chlorophyll a and c, carotenes Leucosin (oily carbohydrates), fats (cytoplasmic droplets). Unicellular flagellates (unequal flagella), colonial, filamentous or coenocytic. Cell wall contains cellulose, hemicellulose, silica. Structure Reproduction Mainly asexual (formation of cysts or aplanospores or vegetative by fragmentation). Occasionally sexual by oogamy e. g. Vaucheria Antheridia are developed by transverse septa formed at the tip of lateral branches with many nuclei but few plastids. Oogonium is formed on the same filament or closely adjacent branch. Genera Vaucheria Ecology Mainly fresh water, wet soil and tree trunks.

Vaucheria sp.

Vaucheria reproduction

Vaucheria sex organs

Class Chlorophyceae Color Nutrition Pigments Stored food Morphology Structure Mostly bright green Photosynthetic Chlorophylls a and b carotenoid Starch Unicellular, colonial, filamentous, multicellular. Cellulosic cell wall Form biflagellate gametes Have vegetative growth in most cases chloroplast vary in shape Chloroplast may contain pyrenoids (center of stachaccumulation) Reproduction Asexual (by fission, fragmentation or formation of motile spores) Sexual (isogamy, anisogamy or oogamy. Genera Unicellular Chlamydomonas colonial Volvox Flamentous Spirogyra multicellular ulva Ecology Most are fresh water some are marine few are terrestrial Importance Biological tools for detection of water pollution Production of organic compounds Some types are used as human food supplements

Chlamydomonas Volvox Spirogyra

Life cycle of Chlamydomonas

Pandorina • Pandorina colony

Spirogyra

Spirogyra conjugation

Volvox sp. • Volvox coenobium

Volvox zygotes

Volvox zygotes

Oedogonium sp.

Oedogonium

Ulva sp.

Physarum

Euglena – example of cellular complexity in Protists

Structure of a Phycobilisome